It all depends what you want to do. NH and Vemont it the fall during the fall colours are a great place to visit. It can be cold at night but the veiws are breath taking. We were there a few years ago and had snow falling at night. It was great sitting around the campfire sipping on a glass of wine and a light snow falling.

I say ditto. The colors of the fall foliage is one of the most noted things of the north east. However some people travel there to escape the heat of the south during summer. I am sure that would not matter to you though being from the cool part of Arizona. If you go in summer I must recommend Acadia N.P. in Maine. An excellent trip.

Fall. I live in CT. That is when I enjoy camping most. Even the beaches are nice.Not so many people around. Just check the campgrounds as many of them close early to mid October. Lots of fairs & festivals if you are into that stuff,